OUR WORKED EXAMPLE
Equipment price is not the installed price.
Our proposed 6 kW inverter and 14 kWh battery package starts with an equipment figure of £3,499. Installation must be added. The illustration below keeps unconfirmed costs visible instead of treating them as free.
| Item | Planning amount | What it means |
|---|---|---|
| Battery + inverter | £3,499 | Equipment only; exact models and VAT treatment to confirm. |
| Installation labour | £1,500 allowance | Our provisional budget, not an agreed installer fee. |
| Equipment + labour subtotal | £4,999 | Not a complete installed price. |
| Accessories allowance | £200 | Provisional; the installer must confirm required materials. |
| Equipment, labour + accessories subtotal | £5,199 | Indicative only; delivery, additional work and VAT treatment remain to confirm. |
| Delivery and extra work | To confirm | Assessed against access, electrical work and final scope. |
| Final consumer total | After assessment | Must include applicable VAT and all agreed work. |
Do not compare this incomplete subtotal directly with another company’s fully installed offer. Ask both suppliers to identify the same inclusions. Our package outline shows the next checks needed.
5 kWh, 10 kWh or 14 kWh: what size do you need?
kWh measures stored energy; kW measures power. A 6 kW inverter with a 14 kWh battery does not store 6 kWh. It combines a power rating with an energy capacity, and the actual output depends on the whole system.
| Capacity class | A useful question | What to check |
|---|---|---|
| Around 5 kWh | Is the energy I want to shift relatively modest? | Usable capacity and evening consumption. |
| Around 10 kWh | Can I regularly charge and use a larger amount? | Solar surplus or cheap-rate window, and daily demand. |
| Around 14–16 kWh | Will I actually use the additional capacity? | Seasonal demand, charge speed and installation space. |
Start with your half-hourly electricity data if available. Look at consumption when solar is not generating or when your tariff is expensive. A larger battery can sit partly unused if the house cannot charge or discharge enough energy. Roof size or bedroom count alone is not enough to choose it.
Ask for usable capacity, the backup reserve and continuous output—not just the model’s headline number. Compare our package options and battery brand guide.
What makes installation more expensive?
Electrical work
Long cable routes, protection equipment, consumer-unit changes and network requirements can change the scope.
Location and access
The installer needs a suitable location, safe access and appropriate mounting. Outdoor suitability is model specific.
Backup functions
Power-cut backup may need a gateway, switching equipment or dedicated circuits. It is not automatically included.
For an existing solar installation, check whether the current inverter stays in place or is replaced. Combining battery work with another installation may reduce duplicated site work, but get the actual combined price. See our installation guide for the questions your final scope should answer.
TRY THE NUMBERS
How much could shifting electricity save?
This calculator explores grid charging on a time-of-use tariff. Enter the energy you expect the battery to deliver to your home on an active day. The example inputs are invented scenarios, not current tariff offers or a prediction for your home.
Annual net energy saving = delivered kWh × active days × (avoided import price − charging price ÷ efficiency), with prices converted from pence. Simple payback = complete installed cost ÷ positive annual saving.
The result excludes degradation, standby use, maintenance, finance costs, future tariff changes and changes to standing charges or other household import rates. It assumes your battery, inverter, charging window and household demand can support the energy entered. A payback longer than the warranty deserves particular scrutiny; even a shorter result is not guaranteed.
What if I charge from solar?
Solar charging needs a separate calculation. Electricity stored instead of exported has an opportunity cost: the export payment you give up. Compare avoided import costs with lost export income, allowing for storage losses. Do not add solar and grid-charging savings for the same stored energy.
Is there VAT on a home battery?
HMRC provides temporary zero-rating for qualifying installations of energy-saving materials in residential accommodation, including qualifying electrical battery storage. The relief runs until 31 March 2027; the reduced 5% rate is scheduled from 1 April 2027. Buying equipment separately is not automatically covered by installation relief.
The supplier must confirm the treatment of your actual contract. We have not assumed that the £3,499 equipment figure qualifies for zero VAT. Check HMRC’s VAT Notice 708/6 for the current rules.
When is a home battery worth considering?
The case is stronger when you can regularly move a meaningful amount of electricity from lower-cost periods to higher-cost periods, or use solar that would otherwise be exported on less favourable terms. It is weaker if little energy passes through the battery or if the price difference is small.
Ask for a calculation based on your actual use and tariff, with the assumptions written down. A warranty is not a savings guarantee. Our battery packages are intended to carry a 10-year manufacturer warranty, subject to the selected model’s conditions; installation cover is separate.
Home battery cost questions.
Can I have a battery without solar panels?
Yes, a suitable system can charge from the grid. Its economics depend on your tariff, charging losses and when you use electricity. It needs professional design and installation.
Does a battery eliminate my electricity bill?
No. Grid imports, standing charges and other costs can remain. Zero Bill Energy is a brand name, not a promise of zero bills.
Can I add storage to existing solar?
Often, but the existing inverter, wiring and proposed battery must be assessed. Ask whether your quote retains the current inverter or includes a replacement.
Why do quotes for the same capacity differ?
Usable capacity, power output, inverter specification, backup hardware, installation work and support can differ. Compare the exact models and scope, not capacity alone.
Do I have to wait for a group to fill?
Our programme combines sourcing demand. Where stock and installer capacity allow, a household may proceed without waiting for a local group. Availability must be confirmed.
Get a clearer starting point.
Explore your package and installation requirements before sharing contact details.
Find my home battery package ↗Sources and pricing basis
General cost reference: Energy Saving Trust battery guide. VAT: HMRC Notice 708/6. The £3,499 equipment figure was supplied by Zero Bill Energy; £1,500 labour is our provisional allowance, not a market quotation. Calculator outputs are arithmetic scenarios. This guide is written by a prospective equipment supplier, not an independent whole-market comparison.